In 3GPP (Third Generation Partnership Project) which is a project aiming to standardize a mobile communication system, an MDT (Minimization of Drive Tests) function has been specified. MDT is primarily a function to optimize a network by measuring a radio environment by the radio terminal and reporting a measurement result together with location information to the network.
Further, in the 3GPP, in order to meet rapidly increasing traffic demands, attempts to improve LTE (Long Term Evolution) are undergoing. As one of such attempts, it has been discussed to use, for LTE communication, not only a licensed frequency band that is a frequency band for which a license is granted to an operator, but also an unlicensed frequency band that is a frequency band for which a license is not required. The unlicensed frequency band may be referred to as “unlicensed spectrum”.